Breast implant and method of manufacture

ABSTRACT

An implantable soft tissue prosthesis comprising a hollow shell formed of a flexible elastomeric envelope, the shell having an inner volume and an exterior surface, when the inner volume is filled with an elastomeric silicone tubing that is preshaped conforming to the inner volume of the shell, the prosthesis being adapted to be surgically implanted in a human breast.

FIELD OF THE INVENTION

The present invention is generally related to soft tissue implantprostheses, such as breast, testicular, tissue expander, and facialimplants, and more particularly, the invention relates to a breastimplant with a filling material and its method of making such implants.

BACKGROUND OF THE INVENTION

Soft tissue medical implants such as mammary prostheses generally aremade of silicone material for an elastomer shell and filling materialdisposed inside the shell. If the shell ruptures, either as a result ofaccidents or through crease-fold flaw or other modes of failure, thefilling material escapes into the body. If the filling material issilicone gel, hydrogel, or gel made from natural biomaterial, theexposure of such a large volume of gel material in the body would pose asignificant risk and complications for both long and short terms. Therisks associated with any of the gel type material have been welldocumented and published in the literature.

If the filling material is saline, saline will excrete readily; however,the deflated shell must be removed and would require another surgery. Inmany cases, it has been reported that the small pieces and fragments ofshell material might migrate to other areas causing further risks andcomplications.

If the filling material is hydrogel made from either synthetic ornatural biopolymer, the long term risks or complications remain unknownbecause little data exists for tissue reactivity of these materials.Furthermore, since the chemistry and characteristics of the hydrogel aresignificantly different from conventional silicone gel, theacceptability of the gel made from material other than silicone stillremains an issue with both physicians and patients.

Soft tissue implants, particularly breast implants, have gone through aconsiderable transition over several years with respect to the safety ofsilicone gel filling materials. As a result, a number of materials havebeen proposed to replace the silicone gel and saline which have beenused over the past 30 years.

U.S. Pat. No. 4,731,081 to Tiffany et al., entire contents of which areincorporated herein by reference, discloses a surgically implantablemammary prosthesis that is rendered rupture-resistant by injecting aliquid with uniformly dispersed lubricating material into a flexiblecreasable shell during manufacture or surgical implantation. Thelubricating material, such as polyvinylpyrrolidone, polyvinyl alcohol,hydroxyethyl starch, or lecithin is uniformly dispersed in a carrierinflating liquid such as normal saline.

U.S. Pat. No. 5,219,360 to Georgiade, entire contents of which areincorporated herein by reference, discloses a surgical mammaryprosthesis containing a liquid-gel of cross-linked hyaluronic acidinside a medical grade elastomer, and a method of making a prosthesiscontaining such a liquid-gel. Because the gel used in the inventioncontains a nontoxic, nonantigenic, noninflammatory, biodegradablenatural substance, problems attributed to or associated with previoussilicone gel filled prostheses as a result of prosthesis rupture orleakage or “bleed” are avoided.

U.S. Pat. No. 5,282,857 to Perry et al., entire contents of which areincorporated herein by reference, discloses a medical implant comprisingan outer envelope and a gel filler material, wherein the gel compriseswater and a cellulose gelling agent. The gel in the implant may furthercontain a lubricating agent. The components of the gel are biocompatibleand do not adversely affect human beings. Implants containing thelubricating agent have a decreased tendency of failure caused byinternal friction on the envelope. The implants of the present inventionhave similar characteristics of the human breast.

U.S. Pat. No. 5,534,023 to Henley, entire contents of which areincorporated herein by reference, discloses an implantable prostheticdevice having a biocompatible elastomeric shell and a polyphasic fillermaterial consisting of gas-filled chambers or beads bathed in abiocompatible fluid. In a preferred embodiment the solid and gaseousphases of the filler comprise interconnecting flexible chains of smallgas-filled beads. The gas-filled beads may be continuously extruded in achain with a fiber of extrudate connecting the beads. In one embodiment,the extruded chains of beads are formed into a mass having the desiredshape of the prostheses where they may be further crosslinked, thenplaced within an outer shell. The void space between the beads is filledwith a biocompatible fluid such as saline.

U.S. Pat. No. 5,549,671 to Waybright et al., entire contents of whichare incorporated herein by reference, discloses a fluid-filled mammaryprosthesis for implantation beneath the skin of a patient comprising ashell and an adjunctive filler. The shell is preferably a closedsilicone elastomer envelope having an interior volume and a valve forfilling. The filler material is a mixture of a fluid such as saline andan adjunct consisting of a plurality of hollow silicone beads having twoor more fenestrations within the wall of each bead which provide fluidcommunication between the outside of the bead and the hollow interior.The beads are packed into the shell prior to the introduction of fluidinto the interior of the shell. The beads serve as a baffle to preventunwanted hydraulic behavior of the fluid portion of the filler materialand also serve to help maintain the anatomical profile of the implant.The hollow beads, which range in sizes from about 7/32 inch to ½ inch ininside diameter, may be conveniently made by injection molding. Theadjunctive filler may be a plurality of beads of a particular size or amixture of different sized beads.

U.S. Pat. No. 5,824,081 to Knapp et al., entire contents of which areincorporated herein by reference, discloses a tissue implant comprisinga flexible shell, a fluid filler within the shell, a compound foam bodydisposed within the shell, the compound foam body comprising a distinctfirst foam region having a substantially uniform first cellular densitythroughout the first foam region, and a distinct second foam regionhaving a substantially uniform second cellular density throughout thesecond foam region, the second cellular density being different than thefirst cellular density, and a cavity in the compound foam body adaptedto provide a hydraulic reservoir for the fluid filler, the cavity beingsubstantially larger than any cell.

U.S. Pat. No. 5,843,189 to Perouse, entire contents of which areincorporated herein by reference, discloses a breast prosthesiscomprising a plurality of pockets filled with a liquid, wherein each ofthe pockets has, at rest, a predetermined configuration, and each of thepockets is delimited by a flexible membrane; and a holding device forholding the pockets against one another, wherein the pockets are formedintegrally with one another so as to form at least one string.

U.S. Pat. No. 5,941,909 to Purkait, entire contents of which areincorporated herein by reference, discloses a new soft tissue implantfilling material. The surgically implantable soft tissue implant fillingmaterial has good aesthetic properties, as measured by viscosity andelasticity. One embodiment of such a new filling material is a gel whichcomprises three components. The first component is a water solublepolymer or hydrogel that has a high molecular weight. Alternatively, thefirst component is both crosslinked and has a high molecular weight. Thesecond component of the filling material is a water-soluble polymer thatis eliminated rapidly through the kidneys upon subcutaneous release. Thethird component of this filling material is saline, which is used todissolve the polymer and to adjust the osmolality of the polymer. Inaddition, a buffer may be added to the filling material to adjust the pHof the gel. One gel formulation of the present invention, in itspreferred embodiment, consists of polyacrylamide and derivativesthereof.

None of the prior art patents recognize or addresses the critical andimportant issues which are involved in the selection of a suitablematerial that would provide a safe and effective implant fillingmaterial.

SUMMARY OF THE INVENTION

It is, therefore, an object of this invention to provide a mammaryprosthesis with a silicone shell containing a filling material made fromsilicone tubing that renders the improvements and benefits as: (1)filling material being made from the same shell material family wouldnot require any new or different biocompatible data and thus wouldprovide a relatively faster regulatory approval; (2) issues related togel migration, bleed and exposure of many low molecular weight chemicalcomponents to the body would be eliminated; (3) in case of rupture, thetubing bundle could be removed easily and would not migrate or excrete;(4) the manufacturing process and method of making the final productwould be simple and less expensive than the current saline or gelmanufacturing process; (5) in case of rupture, there will be no need toremove the implant as no functionality loss is expected thus making theimplant a deflation proof prosthesis; and (6) the implant aesthetic lookand feel would remain equal to or better than the current gel or salineimplant.

It is a further object of this invention to provide a method of makingsuch a compatible filling material which would provide substantiallybetter feel and aesthetic appearance than the current prosthesis.

It is another object of the invention to provide a soft tissueprosthesis to remain functional even after shell rupture from theprosthesis, for examples, a breast, a testicular, a tissue expander, anda facial implant comprising a filling tubing material made of the samematerial of the shell.

Some aspects of the invention relate to an implantable soft tissueprosthesis comprising a hollow shell formed of a flexible elastomericenvelope, the shell having an inner volume and an exterior surface, whenthe inner volume is filled with an elastomeric silicone tubing, theprosthesis being adapted to be surgically implanted in a human breast.In one embodiment, the softness of the silicone tubing ranges from 10 Dto 50 D, wherein the silicone tubing is made from medical grade siliconepolymer that is platinum or peroxide cured. In one embodiment, thesoftness of the silicone tubing is substantially identical to that ofthe shell. In another embodiment, the diameter of the silicone tubing issubstantially constant along its length.

One embodiment of the invention provides the envelope with means forfilling the inner volume with silicone tubing, wherein the means may bea valve, a one-way check valve or a self-closing seal. In oneembodiment, the silicone tubing is filled with a substance selected fromthe group consisting of saline, viscous saline, silicone gel, hydrogel,and thermo reversible polymeric gel. In one embodiment, the prosthesisfurther comprises foam with at least one closed cell having a consistentgel-like feel and durability. In another embodiment, the silicone tubingof the prosthesis is encapsulated with super absorbent hydrogelmaterial, preferably before being filled into the envelope.

Some aspects of the invention relate to an implantable soft tissueprosthesis comprising a hollow shell formed of a flexible elastomericenvelope, the shell having an inner volume and an exterior surface,wherein when the inner volume is filled with a strip of siliconeelastomer made of a material similar to the material for making thehollow shell, the prosthesis being adapted to be surgically implanted ina human body, such as a breast, a testicular, a tissue expander, and afacial.

Some aspects of the invention relate to an implantable mammaryprosthesis to augment or reconstruct natural breast tissue, theprosthesis comprising a hollow shell formed of a medical gradeelastomer, the hollow shell having an inner wall and an inner volumefilled with silicone tubing, wherein the prosthesis is characterizedwith a property of non-deflation upon rupture of the shell. In oneembodiment, the silicone tubing is detectable with mammography orultrasound imaging. In another embodiment, the inner wall is coated withlubricating biocompatible polymer. In still another embodiment, theinner wall is coated with cohesive silicone elastomer selected from thegroup consisting of hyaluronic acid, polyvinylpyrroldine, polyvinylalcohol, lecithin, silicone gel, polyacrylamide, polyethylene oxide,polypropylene oxide, polyethylene oxide/polypropylene oxide (PEO/PPO)combination, polycaprolactone, polylactic/polyglycolic acid, fatty acidesters, fatty acid salts, hydroxyl ethyl starch, methacrylates, andpeptides.

Some aspects of the invention relate to a method of making a mammaryprosthesis, comprising: providing a soft silicone tubing and a hollowshell formed of a flexible elastomeric envelope defining an innervolume; braiding and weaving the silicone tubing to form a desired shapewith softness and durability; and filling the inner volume with theshaped tubing conforming to the inner volume of the shell. In oneembodiment of the present invention, the soft silicone tubing isopen-ended with a lumen space. In another embodiment, the soft siliconetubing is close-ended at both ends. In still another embodiment, thelumen space of the close-ended tubing is filled with a desired fluid orgel.

In one embodiment, the tubing in the method of making a mammaryprosthesis has a softness between about 5 D and 100 D, preferablybetween about 10 D to 50 D, or has an outside diameter between about 0.1to 0.125 inch. Preferably the tubing has an outside diameter of betweenabout 0.15 and 0.3 inch.

Some aspects of the invention relate to a method of making a mammaryprosthesis comprising providing a soft silicone tubing; braiding andweaving the silicone tubing to form a desired shape with appropriatesoftness and durability; dipping the shaped silicone tubing in RTV ormethyl dispersion silicone to form into a self integrated implantadapted for use as the mammary prosthesis.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and features of the present invention will becomemore apparent and the invention itself will be best understood from thefollowing Detailed Description of Exemplary Embodiments, when read withreference to the accompanying drawings.

FIG. 1 shows a top view of a mammary prosthesis of the invention.

FIG. 2 shows a side cross-sectional view of the mammary prosthesisfilled with a filling tubing.

FIG. 3 shows a side cross-sectional view of the mammary prosthesisfilled with a filling tubing that has a coating surface.

FIG. 4 shows a top cross-sectional view of the mammary prosthesis,section I-I of FIG. 3.

FIG. 5 shows one embodiment of the wound tubing prior to being insertedinto a shell of the empty mammary prosthesis.

FIG. 6 shows half of the cross-sectional view of the wound tubing withsurface coating, section II-II of FIG. 5.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The preferred embodiments of the present invention described belowrelate particularly to a soft tissue implant prosthesis, fillingmaterial, and its method of manufacturing. While the description setsforth various embodiment specific details, it will be appreciated thatthe description is illustrative only and should not be construed in anyway as limiting the invention. Furthermore, various applications of theinvention, and modifications thereto, which may occur to those who areskilled in the art, are also encompassed by the general conceptsdescribed below.

FIGS. 1-6 show one preferred embodiment of a mammary prosthesisaccording to the present invention. The present invention is asurgically implantable soft tissue implant with filling material havinga number of novel characteristics, many of which have not heretoforebeen recognized previously or disclosed in the prior art.

FIG. 1 shows a top view of a mammary prosthesis of the invention whereasFIG. 2 shows a side cross-sectional view of the mammary prosthesis 10filled with filling tubing 12. The invention relates to a medicalimplant comprising an outer envelope or shell and silicone tubing asfilling material. The shell 11 may also comprise other features. In oneembodiment, one silicone tubing is the sole filling material, whereinthe filling tubing is sized and arranged to fill most or all of the voidspace within the envelope. In a further embodiment, a plurality ofsilicone tubings is the only filling material.

In an alternate embodiment, a small quantity of lubricants orlubricating material is added inside the envelope adapted forlubrication or friction reduction between sections of the filling tubingor between any section of the filling tubing and an interior surface ofthe shell. For example, lubricating material can be selected from thegroup consisting of silicone oil, saline, gel, hydrogel, other oil,hyaluronic acid, and the like. In a further embodiment, the lubricatingmaterial comprises a plurality of distinct, detached beads with uniformsizes or various sizes, wherein each bead consists of a shell made ofthe same material as that of the envelope of the mammary prosthesis. Theinterior of the beads is filled with gas, liquid or gel to enhanceresilience or elasticity. In some embodiments of the invention, thesilicone beads serve as the lubricating material in the presence of thesilicone tubing or serve as the filler that replaces the silicone tubingin a mammary prosthesis. The lubricating material reduces frictionalwear along opposed inner surfaces during sliding contact in a creasedarea in the shell wall after surgical implantation.

In one embodiment, the tubing softness is in the range from 10D to 50D(measured in durometers, D) with an outside diameter of about 0.10 inchto 0.125 inch or higher. In a further embodiment, the tubing may have asoftness between about 5D and 100D. In one preferred embodiment, thetubing has an outside diameter of between about 0.15 and 0.3 inch. Tomaintain flexibility and integrity of the filling tubing, the tubingthickness is about 0.005 to 0.05 inch, preferably between about 0.01 toabout 0.02 inch. In a preferred embodiment, the cross-section of thetubing has a pair of thicker walls opposite to each other. By ways ofillustration, the average thickness of the cross-section wall of thetubing in each quadrant may be 0.01, 0.02, 0.01, 0.02 inch,respectively. Prior to filling, the tubing is wound into a desirableshape as required by the implant size with a special winding process,for example, a 3-D wound shape. The tubing is fabricated into a desiredshape independently and could be inserted into the shell during finalproduct manufacturing. The shell would be closed with a patch afterfilling and would be ready for sterilization. FIGS.1, 2, and 3 showpatch 16 covering opening 15. In another embodiment, the shell isformed, molded, or cast around the shaped tubing that is sized andconfigured to manufacture a mammary prosthesis. In an alternateembodiment, the filling tubing may be substituted by a filling strip ora flexible elongate filling belt or rod without any internal void spacein the present invention.

The implant filled with medical grade silicone filling tubing or stripwith or without a textured exterior surface can be used for eitheraugmentation or reconstruction of breast or other implantation purposes.In one embodiment, the filling tubing occupies at least 80 percent,preferably about 95%, and most preferably about 99% or more, of theinterior volume 14 of the elastic envelope 11 or prosthetic shell. Byways of illustration, high density packing may be achieved by laying thetubing snugly along the recessed interface of the wound pattern in a3-dimensional manner. FIG. 3 shows a side cross-sectional view of themammary prosthesis filled with a filling tubing that has a coatingsurface whereas FIG. 4 shows a top cross-sectional view of the mammaryprosthesis, section I-I of FIG. 3.

In one embodiment, the silicone tubing is substantially uniform indiameter or cross-sectional area/shape along the length of the tubing.In another embodiment, the cross-sectional area may be a circular shape,an oval shape, a semi-circular shape, a rectangular shape, or othershape. When the interior void of the filling tubing is filled with afluid or gel, the fluid/gel is not in communication with the exteriorportion of the filling tubing. In one embodiment of the presentinvention, the soft silicone tubing is open-ended with a lumen space. Inanother embodiment, the soft silicone tubing is close-ended at bothends. In still another embodiment, the lumen space of the close-endedtubing is filled with a desired fluid or gel.

In another aspect, the invention relates to a method of preparing tubingwound in a suitable shape resulting in the desired softness and volumefor the implant to achieve intended purposes. In one embodiment, thetubing is formed into a flexible woven ball conforming to the innervolume or inner space of the shell. In another embodiment, the siliconetubing is braided and/or woven to form a desired shape with appropriatesoftness and durability.

FIG. 5 shows one embodiment of the wound tubing prior to being insertedinto a shell of the empty mammary prosthesis whereas FIG. 6 shows halfof the cross-sectional view of the wound tubing with surface coating,section II-II of FIG. 5. In one embodiment, the tubing is wound in acontinuous 3-dimensional circular manner similar to a circular-shapedpyramid.

In other aspects, the invention relates to a special RTV (roomtemperature vulcanized silicone) coating as a skin 13 over at least aportion of the wound tubing to ensure the wound tubing holds its shapeproperly and uniformly. Furthermore, the coating would prevent abrasionof the tubing with the shell and thus would provide a longer life of theimplant. The thickness and softness of the coating would further enhancethe feel and aesthetic appearance of the implant. In a furtherembodiment, the coating would fill up the void in between exteriorsurfaces of the wound tubing; increase the occupied volume of the shellspace, thus making a low void mammary prosthesis feasible.

The invention also relates to silicone filling tubing that contains athermo reversible hydrogel, viscous saline made with viscosity enhancerpolymer, or viscous gel inside the sealed or close-ended tubing. In oneembodiment, the silicone tubing contains self-expanding foam or spongeinside the sealed tubing, wherein the self-expanding foam or sponge istriggered to expand by a remote ultrasound, radiofrequency orelectromagnetic energy. The expanded filling tubing would occupy theinterior void space of the envelope to a desired percentage. The foam orsponge matrix, after expanding, is configured sufficiently resilient tosupport the envelope without collapsing.

Some aspects of the invention relate to a medical implant such as amammary prosthesis that is rendered deflation resistant due to fillingwith silicone tubing as a novel solid filling material. In oneembodiment, the tubing is filled with saline or thermo reversiblepolymeric hydrogel. In another embodiment, the mammary prosthesis isfilled with at least one elastomer strip made of silicone. Because thefilling tubing or the filling strip used in the invention is made fromthe identical material used in the envelope or shell of the prosthesis,the biocompatibility, overall safety and efficacy data that currentlyexist would apply for the filling tubing material.

Additionally, problems attributed to or associated with silicone gelfilled prosthesis as a result of prosthesis rupture or leakage or bleedcould be avoided. Rupture or deflation of a saline mammary prosthesiswould require the shell to be removed as the deflated shell would looseits functionality. The mammary prosthesis of the present invention wouldremain functional and might not need to be removed upon rupture of theshell because the shaped silicone tubing would retain its shape andstrength and would likely maintain its functionality.

In case of a catastrophic failure of the envelope, the filler tubing orstrip material (elongate filling material) could be removed easily bypulling one end of the silicone filling tubing/strip and the wholeelongate filling material is removed thereafter. However, the gelfilling material of a conventional mammary prosthesis would disperse toother parts of the tissue and would potentially pose a long term risks.

The novel and unique characteristics of the invention are outlined asfollows:

-   -   1) the filling tubing or strip made from identical material as        shell is compatible with the shell and other components of the        implant;    -   2) the filling tubing or strip would not migrate, does not have        bleed, will not collapse because of rupture, can be easily        retrieved, will not interfere with mammography and will remain        stable and last longer even upon the rupture of the shell;    -   3) the softness, feel and consistency of prosthesis (shape and        volume) will be controlled by the winding technique and method        of winding for the filling tubing;    -   4) due to the identical chemical, physical and biological        properties of the filling tubing with the shell material, the        regulatory requirements will be similar. As a result the        submission for regulatory approval would be faster and less        burden; and    -   5) the manufacturing of the breast prosthesis would be less        expensive as winding of the filling tubing could be done        separately and the final product could be assembled by inserting        the wound tubing and patching the shell.

From the foregoing, it should now be appreciated that a mammaryprosthesis filled with filling tubing or strip of the same shellmaterial has been disclosed. While the invention has been described withreference to a specific embodiment, the description is illustrative ofthe invention and is not to be construed as limiting the invention.Various modifications and applications may occur to those skilled in theart without departing from the true spirit and scope of the invention asdescribed by the appended claims.

1. An implantable soft tissue prosthesis adapted to be surgicallyimplanted in a human breast consisting essentially of a hollow outershell defining an inner void volume filled with an elastomeric siliconeunfilled tubing, said outer shell is formed of a flexible elastomericenvelope and wherein said unfilled tubing is of medical grade platinumor peroxide cured silicone polymer; said elastomeric silicone tubinghaving a length and an outside diameter substantially uniform along saidlength of between about 0.1 and 0.125 inch, a thickness between about0.005 and 0.05 inch, and a softness ranging from about 5D to 50 D; andwherein the void between said silicone tubing being unfilled.